1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method, and to a storing medium, and more particularly to an image processing apparatus and method suitable for application to a digital copier, a scanner or the like, and to a storing medium.
2. Related Background Art
An image processing apparatus such as a digital copier and a scanner is known, which reads an image of an original placed on an original support and executes predetermined image processing. In a conventional image processing apparatus, a timing signal is generated in accordance with a clock signal having a fixed frequency generated by a clock signal generation unit such as a quartz oscillator, and synchronously with this timing signal, an original image is read to generate image data which is subjected to various image processing.
With recent high speed and high resolution of sophisticated image processing techniques, the frequency of a clock signal to be used for the image processing by an image processing apparatus is becoming high. On the other hands, regulations on noises radiated from various electronic apparatuses are becoming sever one year after another. If the clock frequency is raised; as in recent years, it is predicted that countermeasures against radiation noises of an image processing apparatus become more difficult. In order to meet the specifications of electromagnetic interference (EMI) adopted worldwide, it is necessary to suppress the amount of radiation noises, which results in a smaller degree of design freedom, a larger load upon a designer and a technical person, and a rise of manufacture cost.
As countermeasures against such radiation noises, there is a method of modulating the frequency of a clock signal. However, if image data is processed by using a timing signal generated in accordance with a frequency-modulated clock signal, there occurs a problem that when the processed image data is output on a recording apparatus such as a printer, the size of each dot becomes different. Furthermore, an abnormal operation, if any; of a frequency modulation function cannot be notified to a user.
It is an object of the present invention to output image data processed synchronously with a frequency-modulated clock signal without any practical problem.
It is another object of the present invention to allow an operator to confirm the operation state of a frequency modulation function.
According to embodiments of the present invention, the following image processing apparatus, image processing method, and storage medium storing program codes for realizing the image processing method are provided.
An image processing apparatus comprises: a modulation circuit for frequency-modulating a clock signal; a memory for storing image data; a write circuit for writing image data in the memory, synchronously with a first clock signal frequency-modulated by said modulation circuit; and a read circuit for reading image data from the memory, synchronously with a second clock signal having a fixed frequency.
An image processing apparatus comprises: an image reading unit for reading an original image; an image processing circuit for subjecting an image signal read with the image reading unit to a predetermined image processing operation; a first clock generation circuit for generating a first clock signal to be used for processing the image signal; a frequency modulation circuit for frequency-modulating the first clock signal output from the first clock generation circuit; a first timing signal generation circuit for generating a first image processing timing signal in accordance with the first clock signal frequency-modulated by the frequency modulation circuit; an image data generation circuit for processing the image signal synchronously with the first image processing timing signal generated by the first timing signal-generator circuit to generate image data; a second clock generation circuit for generating a second clock signal; a second timing signal generation circuit for generating a second image processing timing signal in accordance with the second clock signal output from the second clock generation circuit; a write circuit for writing the image data generated by the image data generation circuit in a memory, synchronously with the first timing signal generated by the first timing signal generation circuit; a read circuit for reading image data from the memory, synchronously with the second timing signal generated by the second timing signal generation circuit; and an image processing circuit for processing the image data read from the memory.
An image processing method comprises: a modulation step of frequency-modulating a clock signal; a write step of writing image data in a memory, synchronously with a first clock signal frequency-modulated at said modulation step; and a read step of reading image data from the memory, synchronously with a second clock signal having a fixed frequency.
An image processing method comprises: an image reading step of reading an original image; an image processing step of subjecting an image signal read at the image reading step to a predetermined image processing operation; a first clock generation step of generating a first clock signal to be used for processing the image signal; a frequency modulation step of frequency-modulating the first clock signal generated at the first clock generation step; a first timing signal generation step of generating a first image processing timing signal in accordance with the first clock signal frequency-modulated at the frequency modulation step; an image data generation step of processing the image signal synchronously with the first image processing timing signal generated at the first timing signal generator step to generate image data; a second clock generation step of generating a second clock signal; a second timing signal generation step of generating a second image processing timing signal in accordance with the second clock signal generated at the second clock generation step; a write step of writing the image data generated at the image data generation step in a memory, synchronously with the first timing signal generated at the first timing signal generation step; a read step of reading image data from the memory, synchronously with the second timing signal generated at the second timing signal generation step; and an image processing step of processing the image data read from the memory.
A storage medium storing a program for realizing an image processing method, the method comprises: a modulation step of frequency-modulating a clock signal; a write step of writing image data in a memory, synchronously with a first clock signal frequency-modulated at said modulation step; and a read step of reading image data from the memory, synchronously with a second clock signal having a fixed frequency.
A storage medium storing a program for realizing an image processing method, the method comprises: an image reading step of reading an original image; an image processing step of subjecting an image signal read at the image reading step to a predetermined image processing operation; a first clock generation step of generating a first clock signal to be used for processing the image signal; a frequency modulation step of frequency-modulating the first clock signal generated at the first clock generation step; a first timing signal generation step of generating a first image processing timing signal in accordance with the first clock signal frequency-modulated at the frequency modulation step; an image data generation step of processing the image signal synchronously with the first image processing timing signal generated at the first timing signal generator step to generate image data; a second clock generation step of generating a second clock signal; a second timing signal generation step of generating a second image processing timing signal in accordance with the second clock signal generated at the second clock generation step; a write step of writing the image data generated at the image data generation step in a memory, synchronously with the first timing signal generated at the first timing signal generation step; a read step of reading image data from the memory, synchronously with the second timing signal generated at the second timing signal generation step; and an image processing step of processing the image data read from the memory.
With the above embodiment structures, image data processed synchronously with a frequency-modulated clock signal can be output without any practical problem.
According to other embodiments of the invention, the following image processing apparatus and image processing method are provided.
An image processing apparatus comprises: a clock signal generation circuit for generating a clock signal; a frequency modulation circuit for modulating a frequency of a generated clock signal; and a detection circuit for detecting an operation state of the frequency modulation circuit.
An image processing method comprises: a clock signal generation step of generating a clock signal; a frequency modulation step of modulating a frequency of a generated clock signal; and a detection step of detecting an operation state of frequency modulation.
With the above embodiment structures, the operation state of a frequency modulation function can be confirmed.
Other objects and features of the present invention will become apparent from the following specification and the accompanying drawings.